Too many people are unaware obesity is linked to cancer, and believe the main reason to lose weight is to look good, a survey suggests.
Obesity is linked to several cancers
Cancer Research UK says its findings show a worrying lack of knowledge.
The poll of over 4,000 adults found 40% thought looking good was a reason to maintain a healthy weight, while 32% knew it lowered cancer risk.
Obesity increases the risk of cancers including bowel, stomach, oesophageal and kidney, womb and breast cancers.
Cancer experts warn that being obese or overweight is one of the most significant preventable causes of cancer in non-smokers.
Rates of obesity are increasing throughout the UK.
In the poll, people were asked to choose why it was good to lose weight.
Younger people were the most image-conscious.
Almost half - 48% - said looking good was a reason for being a healthy weight, with only 34% identifying cancer risk as a motivating factor.
But in the over-65 age group, looking good and cancer risk were equal reasons for those over 65 with 25% listing both.
Overall, it was found 67% - twice as many as knew about cancer risks - realised losing weight reduced the risk of heart disease.
Cancer Research UK has now linked up with the charity Weight Concern to offer a simple weight management programme, which has advice about eating a healthy and balanced diet and building regular exercise into daily life.
People are also urged to stop smoking and to protect themselves in the sun.
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "This research provides a real insight into the priorities many of us have when it comes to looking after our bodies and the low awareness of the link between obesity and cancer.
"We know for those who don't smoke, maintaining a healthy body weight is one of the most important things we can do to reduce our risk of cancer."
Professor Jane Wardle, director of Cancer Research UK's health behaviour unit, said: "It is alarming is that so many people are unaware that reducing cancer risk is a benefit of maintaining a healthy body weight.
"We need to continue raising awareness of the dangers of obesity, and offer information to help people lose those extra pounds."